1. Field of the Invention
The present invention relates to the technical field of a power supply device used in a light emitting diode (LED) lamp, and more particularly to the LED driving device with open circuit protection and color temperature and brightness adjustment, and a simple jump is provided for flexibly adjusting the light color of the lamp to enhance the adaptability of the product.
2. Description of the Related Art
At present, most LED lamp driving devices employ a switching power converter as the main circuit architecture, and the switching power converter generally includes a fly-back, forward, boost, buck, push-pull, half-bridge or full-bridge circuit. For instance the driving device 1 as shown in FIG. 1 adopts a boost power converter as the main circuit architecture to provide the function of increasing the input voltage to a voltage level required by a load, and the boost power converter comprises a dimming module 10, a rectification module 11, a control module 12 and an output module 13, wherein the control module 12 includes a control chip 120, a protection resistor 121, the transistor 122 and the sensing resistor 123. The dimming module 10 is a tri-electrode AC switch (TRIAC), and the sensing resistor 123 is coupled to the LED through the transistor 121, such that when the TRIAC switches a conduction angle of the input voltage to adjust the brightness, the sensing resistor 123 senses a driving current of the LED to form a voltage drop provided for the control chip 120 to compare the voltage drop with the input voltage to output a high level voltage or a low level voltage to the transistor 122, so as to conduct or cut off the transistor 122 timely to control the duty ratio of a pulse width modulation (PWM) signal and the intensity of the outputted driving current, and affect the brightness of the LED. To prevent the driving device 1 from being damaged by an overvoltage of the circuit, the control chip 120 intercepts the driving voltage outputted from the output module 13 through the protection resistor 121 to determine whether the operation of the overall circuit is normal. However, if an LED of the aforementioned LED string is damaged to form an open circuit, the remaining LEDs will receive the whole voltage outputted by the output module 13 directly, so that these LEDs may be able to work normally, but they may be damaged by the over-voltage after a certain period of time of the operation, and the service life of the lamp will be reduced or the product quality or user satisfaction will be lowered.
In addition, the conventional lamps adopts a combination of the blue light LED and the yellow light LED to produce the required light color of the lamps, but the number of blue light LEDs and yellow light LEDs is determined at the stage of research and development, and users cannot make any adjustment (or increase/decrease the number of blue light LEDs or yellow light LEDs in practical applications) afterwards even the produced lamps may have a light color problem due to the physical properties of different LEDs. Therefore, related manufacturers may have to eliminate the products with the issues of color difference during the inspection before shipping out the product and thus resulting in a poor yield rate and increase the inventory of secondary-quality products.
In view of the aforementioned problems, it is a main subject for the present invention to use a combination of blue and yellow light LEDs in the lamp as the light source, while using a simple switch to flexibly adjust the light color of the lamp before shipping the lamp in order to achieve the effects of assuring the product quality, reducing the defective rate and production cost, and achieving the cost-effectiveness.